Electrolytic pilot igniter



June 30, 1970 w. R. STAATS ETAL 3,518,036

ELECTROLYTIC PILOT IGNITER Filed Aug. 13, 1968 SOURCE OF POWER F/GZ 242:01 INVENTOR. WILLIAM R. STAATS 22 BY ROBERT E. ROSENBERG ESHER R.KWELLER fiat/1% ATTYS.

United States Patent US. Cl. 431-268 7 Claims ABSTRACT OF THE DISCLOSUREA pilot igniter which includes, generally, a cold solid catalyst afiixedin operative relationship with a gas pilot to be ignited and anelectrolytic cell which is adapted to be energized to form hydrogen andoxygen which is mixed with the gas being conveyed to the gas pilot. Thehydrogen is reacted by the cold solid catalyst to, in turn, ignite thegas mixture. The oxygen enhances the ignition. Suitable switching meansare provided and are operated to control the flow of gas to the gaspilot, and to energize and de-energize the electrolytic cell to controlthe flow of hydrogen, and oxygen, which is mixed with the flow of gas tothe pilot.

This invention relates to an improved ignition process for ignitingnatural gas and to the apparatus for carrying out the same.

Most gas appliances such as, for example, gas ranges and ovens, hotwater heaters and the like, have a continuous standing pilot forigniting their main burners, to operate the appliance. Manymanufacturers have attempted to eliminate the need for such a continuousstanding pilot, by using a heated wire ignition system or electric sparkgenerators to ignite the pilot and/or the main burner. Such systems,however, are objectionable since they are costly and, furthermore,present considerable maintenance problems.

In the past, gas appliances such as those mentioned above were operatedon manufactured gas, and the latter contained a large fraction ofhydrogen. Substantially, if not all, gases containing a large fractionof hydrogen can be catalytically ignited, using a true catalyticignition system, that is, an ignition system employing a cold catalyst,such as a platinum catalyst, having no external energy supplied to it tomake it active. The cold catalyst, when exposed to such a gas, wouldheat up to a high enough temperature to ignite the gas. Accordingly, atrue catalytic pilot igniter for these gas appliances could beconstructed.

Presently, most, if not all, gas appliances operate on natural gasrather than manufactured gas, and natural gas contains mostly methane.Numerous attempts have been made by those skilled in the art, toconstruct a true catalytic igniter for natural gas, however, none ofthese attempts have been successful. In fact, the reports given on theseprior attempts generally conclude that methane cannot be catalyticallyignited by a solid catalyst below approximately 200 F. Accordingly,presently no known cold catalyst exists for natural gas, particularlymethane. True catalytic ignition systems therefore are not now in use.

These reports, however, do propose several alternatives such as, forexample, using two different catalysts. The first catalyst ispre-ignited and provides for the initial 3,518,036 Patented June 30,1970 temperature. The second catalyst is heated by the first andprovides for the temperature boost to the ignition level.

Another alternative is to use electrical energy to provide for theinitial temperature rise, and a catalyst for the further temperatureincrease to ignition level. Accordingly, in this case, the catalystmerely reduces the amount of required electrical energy.

These proposed alternatives may function to provide ignition of thenatural gas, however, they are generally impractical and have not beenaccepted by the industry.

A recent patent, US. Pat. 3,299,675, concerned with a gas-fueledlighter, recognizes the fact that most combustible gases, in particularmethane, butane, propane, etc., if they oxidize at all in the presenceof a platinumbased catalyst, lead to slow combustion and cannot reach atemperature sufficient to generate a flame. This shortcoming, accordingto this patent, is eliminated and ignition assured by the exothermicdecomposition of peroxide on a catalyst and by the favorable presence ofmonatomic oxygen produced by this decomposition. Such a system may bepractical for the particular application disclosed, a gas-fueledlighter, however, it is impractical for general application in gasappliances such as gas ranges and ovens, hot water heaters and the like.For example, the apparatus and mechanism required to contain and toconvey the peroxide to the catalyst is overly complex, too difiicult toinstall and maintain, and prohibitively costly. Also, it is generallywell known that peroxide is extremely unstable, and storing peroxide, inthe concentration suggested, in sufiicient quantity to satisfy therequirements for the applications toward which the present invention isconcerned would create an extremely hazardous condition.

Accordingly, it is an object of the present invention to provide animproved apparatus and ignition process for igniting natural gas.

More particularly, an object is to provide an improved apparatus andtrue catalytic ignition process for igniting natural gas, using a coldcatalyst.

Still another object is to provide improved apparatus and true catalyticignition process; for igniting natural gas, wherein a small amount ofhydrogen is mixed with the natural gas and is ignited catalytically.

A still further object is to provide improved apparatus and truecatalytic ignition process of the above type, wherein the hydrogen mixedwith the natural gas is formed by electrolysis of water.

A further object is to provide improved apparatus and true catalyticignition process of the above type wherein only a small amount ofhydrogen is mixed with the natural gas for a few seconds to start theignition reaction.

Another object is to provide improved apparatus and true catalyticignition process of the above type wherein very little water is consumedduring each ignition, so that only a small water supply, approximately12 ounces, need be provided to operate the igniter to provide more thanthe average number of ignitions which normally would be made each dayfor an extended period of time, approximately one year, before the Watersupply need be replenished.

Still another object is to provide improved apparatus and true catalyticignition process of the above type which requires only a small amount ofelectrical power to operate the same to provide an ignition.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The above objectives are accomplished with an ignition process whichincludes, generally, mixing a small amount of hydrogen with natural gas,impinging the mixture of hydrogen and natural gas onto a cold solidcatalyst, that is, one at ambient temperatures, to cause the latter toheat up to a high enough temperature to ignite the mixture, and stoppingthe flow of hydrogen which is mixed with the natural gas after ignitionhas occurred. The natural gas flow continues and maintains a stablepilot.

The apparatus for providing the ignition process includes, generally, acold solid catalyst aflixed in operative relationship with a gas pilotto be ignited and an electrolytic cell which is adapted to be energizedto form hydrogen and oxygen which is mixed with the gas being conveyedto the gas pilot. The hydrogen is reacted by the cold solid catalyst to,in turn, ignite the gas mixture. The oxygen enhances the ignition.Suitable switching means are provided and are operated to control theflow of gas to the gas pilot, and to energize and de-energize theelectrolytic cell to control the flow of hydrogen, and oxygen, which ismixed with the flow of gas to the pilot.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others and theapparatus embodying features of construction combination of elements andarrangement of parts which are adapted to effect such steps, all asexemplified in the following detailed disclosure, and the scope of theinvention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing in which:

FIG. 1 is a diagrammatic view generally illustrating the constructionand electrical circuitry of an exemplary true catalytic pilot ignitionsystem; and

FIG. 2 is a partial view of the ignition system of FIG. 1, illustratingan alternative arrangement of the electrical circuitry thereof.

Referring now to the drawing, the catalytic pilot ignition system can beseen to include an electrolytic cell having a pair of electrodes 12 and13 which are aflixed within a reservoir 14, preferably in verticallydisposed spaced relation. The reservoir 14 includes means (not shown)for replenishing and maintaining the supply of the electrolyte materialdisposed within it, and has an opening 16 coupled to a pilot gas supplyline 18. The electrolyte material preferably and advantageouslycomprises water, but can be any suitable aqueous solution of acids,alkalis or salts. The reservoir 14 preferably has a capacity ofapproximately 12 fluid ounces, so that sufficient electrolyte materialto provide for approximately 26 ignitions per day, each day, for oneyear, is available.

The electrodes 12 and 13 are electrically coupled to respective ones ofthe output terminals of a secondary winding 20 of a transformer 22, theprimary winding 24 of which is coupled to a source of power 26 which maybe a 110 volt source normally found in most homes and oflices. Arectifier 28 preferably is included in the coupling between theelectrodes 12 and 13 and the secondary winding 20 of the transformer 22,so that each of the electrodes is established or caused to assume apredetermined polarity. The rectifier 28 can be eliminated, if desired,however, improved results are provided with its use. A normally openedswitch 30 is included in the electrical coupling between the primarywinding 24 of the transformer 22 and the source of power 26 and isoperative to control the energization of the transformer 22,

and hence the electrolytic cell 10, in a manner described more fullybelow.

The catalytic pilot ignition system further includes a gas pilot 34which is coupled to the pilot gas supply line 18. The gas pilot 34 is inclose proximity to and is operative to ignite a main gas burner 36 whichis coupled to a main burner gas supply line 38. The pilot gas and mainburner gas supply lines 18 and 38 both are coupled to a main gas line 40which is coupled to a source of a natural gas (not shown). The main gasline 40 includes a control valve 42 and an orifice 43 which is operativeto control the flow of natural gas to the main gas burner 36 and the gaspilot 34 and which is coupled to and operative to open and close thenormally opened switch 30. The control valve 42 has three positions, anoff position, an ignition position and a burner position. When in itsofl position, the flow of natural gas to the main gas burner 36 and thegas pilot 34 is cut off, and the switch 30 is open. When it is operatedto the ignition position, natural gas is permitted to flow to the maingas burner and the gas pilot, and the switch 30 is closed to causeignition of the gas pilot and hence the main gas burner, in the mannerdescribed below. After ignition, the control valve 42 is operated to itsnormal operating position and, in this position, the flow of natural gascontinues, but the switch 30 is again opened.

A catalyst 46 is positioned with respect to the gas pilot 34 such thatthe gas flowing from the gas pilot 34 is impinged upon it. It isgenerally well-known that some catalysts are adversely affected by heator some combustion products. If the particular catalyst used is of thisnature, it should be properly protected. This may be accomplished inseveral suitable fashions, for example by aflixing the catalyst 46 to abi-metallic element which upon being heated, is adapted to move thecatalyst out of the pilot flame.

The operation of the catalytic pilot ignition system can be generallydescribed as follows. Control valve 42 is manually operated to itsignition position, to permit natural gas to flow to the main gas burner36 and the gas pilot 34 and to close the normally opened switch 30. Whenswitch 30 closes, the primary winding 24 of the transformer 22 isenergized, from the source of power 26, and current is induced in andflows through the secondary winding 20, to electrodes 12 and 13 of theelectrolytic cell 10. Electrolysis occurs, for reasons well-known, andhydrogen and oxygen are produced. The hydrogen and oxygen is picked upby the natural gas flow through the opening 16 in the top of thereservoir 14 and is mixed with and carried by the natural gas flowingthrough the gas pilot supply line 18 to and through the orifice of thegas pilot supply line 18 and through the orifice of the gas pilot 34. Animportant aspect is that the hydrogen and oxygen is picked up and mixedwith the natural gas, by sweeping the latter over the top of thereservoir, before the hydrogen and oxygen have an opportunity to reactwith one another. The hydrogen, with oxygen, upon being impinged on thecatalyst 46, causes the latter to heat up to a temperature sufficient toignite the hydrogen and hence the natural gas flowing from the gas pilot34. An added advantage results from the oxygen which is produced andlikewise added to the gas stream, since this oxygen enhances theignition process. The gas pilot 34, upon being ignited, in turn, ignitesthe main burner flame. As indicated above, once the gas pilot isignited, the con trol valve 42 is operated to its burner position, whichoperation opens the switch 30 and hence the energizing circuit for theprimary winding 24 of the transformer 22. The electrolytic cell 10therefore is de-energized, stopping the generation and flow of hydrogenand oxygen into the natural gas stream in the gas pilot supply line 18.The pilot flame and the main burner flame, however, remain lit. Stoppingthe generation of hydrogen and oxygen, once the gas pilot is ignited,conserves the electrolyte in the reservoir 14 so that very little of theelectrolyte material is consumed during each ignition. Electrolysistakes place for only a very short time, approximately 3-5 seconds duringeach ignition, hence only approximately 1 ounce of water is required for780 3-second ignitions. Accordingly, a 12 ounce supply will besuflicient for 26 ignitions per day, every day for one year.

" Also, very little electrical power is required, since onlyapproximately 2.5 .volts and a current flow of 13.6 amps is required tooperate the electrolytic cell 10. Accordingly, it can be seen that lessthan 35 watts of electrical power is required. ,7

To turn off the main burner 36, and the gas pilot 34, the control valve42 is merely operatedto its ofi position. In this position, the switch30 remains open and power is cut off from the transformer 22.

An alternative electrical circuit is illustrated in FIG. 2. In thiscircuit, a temperature sensor 50 is affixed in close proximity to thegas pilot 34 and is adapted to open a normally closed switch 32 when thegas pilot ignites, to stop the flow of electric current to theelectrolytic cell. The temperature sensor 50 can be and preferably iscoupled to and adapted to operate a conventional flame safety valve, inthe event the gas pilot fails to ignite or is blown out or otherwiseextinguished. The normally closed switch 32 is connected in a seriescircuit with the switch 30 and the source of power 26. The control valve42, in this case, also can be merely a two position valve, having an offposition and a burner position, since the switch 32 functions to openthe energizing circuit for the electrolytic cell 10. In all otherrespects, the ignition system operates in the above described fashion.

The catalyst 46 can be any catalyst that is active with hydrogen, suchas for example, platinum or palladium. The catalyst 46 can be afiixed toa refractory support such as alumina, silica, zirconia, thoria, anymixture of refractory material, and even metals, such as platinumitself, if desired. Furthermore, it is generally well-known that somecatalysts will cause reaction to proceed faster and will heat up to atemperature suflicient to ignite the gas mixture (the natural gas,hydrogen and oxygen) quicker than others when hydrogen andoxygen isimpinged on them. This reaction rate also is dependent on numerous otherfactors, such as the surface area of the catalyst, the orifice size andthe flow rate of the gas mixture, to mention but a few of them.Accordingly, once the catalyst is selected, the required orifice size,the flow rate of the gas mixture and the proper proportion of naturalgas, hydrogen and oxygen to provide ignition can be determinedexperimentally.

As an example, in one experimental ignition system which was constructedand tested, a catalyst was fabricated by moistening a small piece ofmullite (a commercial mixture of refractory metal oxides) withchloroplatinic acid and heating it to reduce the platinum salt tometallic platinum. The catalyst was aflixed so that the gas mixture fromthe gas pilot was impinged upon it. The orifice of the gas pilot had adiameter of .0250 inch. A fuel mixture consisting of 54% hydrogen, 27%oxygen and 19% natural gas, flowing through a pilot orifice at a rate of0.37 cubic feet per hour, was required to provide ignition and toprovide a stable natural gas flame. This mixture corresponded to a flowof 0.07 cubic feet per hour of natural gas and a flow of 0.3 cubic feetper hour of hydrogen and oxygen in the proportions that they areproduced by electrolysis of water. If the natural gas content wasreduced much below this value, the flame would flash back through thepilot orifice; and if increased much above this value, the fuel mixturecould not be ignited with the solid cold catalyst. When the pilot flameignited, the flow of hydrogen and oxygen was subsequently stopped andthe natural gas continued to flow at its established rate of 0.07 cubicfeet per hour. This rate is a typical flow rate for a gas range topburner pilot.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efiiciently attained and,since certain changes may be made in carrying out the above method andin the construction set forth without departing from the scope of theinvention, it is intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention, which, as amatter of language, might be said to fall therebetween.

Now that the invention has been described, what is claimed as new anddesired to be secured by Letters Patent is:

1. A catalytic ignition for igniting natural gas comprising, incombination: a gas pilot coupled to a source of natural gas; controlvalve means for controlling the flow of natural gas from said source tosaid gas pilot; a source of hydrogen comprising an electrolytic cell forproviding and mixing hydrogen with the flow of natural gas from saidsource to said gas pilot; a catalyst active with hydrogen positionedwith respect to said gas pilot such that the flow of natural gas and thehydrogen mixed with it is impinged upon and causes said catalyst to heatto a sufiicient temperature to ignite the hydrogen and hence the naturalgas; and means for controlling the flow of hydrogen from said source ofhydrogen comprising a source of power coupled to said electrolytic cell,a normally open switch means electrically included in said couplingbetween said source of power and said electrolytic cell, said controlvalve means further being operable to open and close said normally openswitch means.

2. A catalytic ignition system, as claimed in claim 1, further includinga normally closed switch means electrically included in said couplingbetween said source of power and said electrolytic cell, and temperaturesensing means, said control valve means being operable to open and closesaid normally open switch means and said temperature sensing means beingoperable to open and close said normally closed switch means.

3. A catalytic ignition system, as claimed in claim 1, wherein saidelectrolyte for said electrolytic cell comprises water.

4. A catalytic ignition system, as claimed in claim 1, wherein saidmeans for controlling the flow of hydrogen from said source of hydrogenfurther includes transformer means having a primary winding electricallyincluded in said coupling between said source of power and saidelectrolytic cell and a secondary winding having its output terminalscoupled to respective ones of the electrodes of said electrolytic cell.

5. A catalytic ignition system, as claimed in claim 1, wherein saidcontrol means and said source of hydrogen are operative to deliver afuel mixture to said gas pilot comprising 54% hydrogen and 27% oxygen ata rate of 0.3 cubic feet per hour and natural gas within a range of17-21% at a rate of 0.07 cubic feet: per hour.

6. A catalytic ignition for igniting natural gas comprising, incombination: a gas pilot coupled to a source of natural gas; controlvalve means for controlling the flow of natural gas from said source tosaid gas pilot; a source of hydrogen comprising electrically operatedmeans for dissociating water or a water containing material forproviding and mixing hydrogen with the flow of natural gas from saidsource to said gas pilot; a catalyst active with hydrogen positionedwith respect to said gas pilot such that the flow of natural gas and thehydrogen mixed With it is impinged upon and causes said catalyst to heatto a suflicient temperature to ignite the hydrogen and hence the naturalgas; and means for controlling the flow of hydrogen from said source ofhydrogen comprising a source of power coupled to said electricallyoperated means, a normally open switch means electrically included insaid coupling between said source of power and said electricallyoperated means, said control valve means further being operable to openand close said normally open switch means.

7. A catalytic ignition, as claimed in claim 6, wherein saidelectrically operated means for dissociating water cell.

or a water containing material comprises an electrolytic ReferencesCited UNITED STATES PATENTS 8 3,356,600 12/1967 Henes "1431-2 XRFREDERICK'L. MATTESON, JR., Primary Examiner R; A. DUA, AssistantExaminer Huber.

